Miori Kishimoto

Comparison of the diagnosis of intervertebral disc herniation in dogs by CT before and after contrast enhancement of the subarachnoid space

Eleven miniature dachshunds with a herniated intervertebral disc were examined by CT, first before and then after contrast enhancement of the subarachnoid space. The images were classified into three grades by three veterinarians. In four cases, lesions observed on the scans obtained after contrast enhancement had not been observed on the preliminary scans and in one case a lesion observed on the preliminary scan was not observed on the scan obtained after contrast enhancement. Hemilaminectomies were performed on the basis of the enhanced CT results, and a clinical improvement was observed in each of the dogs. Calcification was detected in all the samples of herniated intervertebral disc material.

Clinical experience of using multidetector-row CT for the diagnosis of disorders in cattle

To determine the clinical usefulness of multidetectorrow CT for the diagnosis of disorders in cattle, images were obtained from 27 cattle, which were then subjected to postmortem and histopathological examinations. The cattle were divided into three categories of disorder: neurological (18 cases), skeletal (four cases) and other (five cases). In five cattle, which were suspected to have brain diseases, no abnormalities were identified by either CT or histopathological examination. Eight types of lesions were detected by CT in the cattle with neurological and vestibular disorders. The diseases diagnosed included hydrocephalus (three cases), intracranial arachnoid cysts (three cases), otitis media (five cases), cerebral abscess (one case), meningoencephalocele (one case), porencephaly (one case), bicephalus (one case) and rupture of the spinal cord (one case). Lesions were identified in all the cattle with skeletal disorders, including luxation (two cases), fracture (two cases), spondylosis (one case) and congenital disorders of the skeletal system (one case). Morphological disorders in the eyes (one case), nasal cavity (two cases), frontal sinuses (one case), thyroid glands (two cases), lung fields (two cases) and abdominal organs (two cases) were diagnosed by CT.

Computed tomography (CT) observation of pulmonary emboli caused by long-term administration of ivermectin in dogs experimentally infected with heartworms

Some studies have reported the adulticidal effect of long-term ivermectin (IVM) administration on adult heartworms in canines; however, there are no detailed reports on the course of the pulmonary artery embolism caused by the bodies of dead heartworms during the administration period. In this study, the pulmonary embolism caused over time by the dead worms was observed using computed tomography (CT). We subcutaneously inoculated 2 beagles with 100 infective third-stage larvae (L3) of Dirofilaria immitis. The dogs were orally administered a formulation containing 272 microg of IVM and 652 mg of pyrantel pamoate (Panamectin Chewables P272; Meiji Seika, Tokyo, Japan) at monthly intervals, beginning from 10 months after the subcutaneous inoculation. Along with IVM administration, periodic CT examination of the chest was performed. At 15 months after the initiation of IVM administration, the dogs were euthanized, the living heartworms were collected, and histopathological examination was performed. Starting from 1 month after the IVM administration, peripheral dilation of the pulmonary artery (suspected to be pulmonary embolism) and pneumonia were observed in the CT images; however, these findings improved over time. The appearance and disappearance of these lesions were observed in all the lobes during the IVM administration period. During this period, the clinical symptoms of pulmonary embolism were not recognized. After 1 month of IVM administration, chest radiographic examination revealed radiopaque lesions in 1 dog. Only some of the lesions detected by CT could be detected by radiography. Using echocardiography, heartworms were observed in the pulmonary arteries of both dogs from 6 months after subcutaneous inoculation to the end of the study period. Microfilaria disappeared from the peripheral blood at 1 month after IVM administration in 1 dog, and at 7 months in the other dog. The adult heartworm antigen test yielded positive results starting from 6 months after subcutaneous inoculation in 1 dog and after 7 months in the other dog; these results remained positive until the end of the study period. After the initiation of IVM administration, the ALP and CK levels were transiently elevated. The number of surviving adult worms collected at necropsy was 25 in 1 dog and 31 in the other. Histopathological examination revealed that the peripheral pulmonary artery dilation detected by CT was the embolus that resulted from the bodies of the dead heartworms. Moreover, vessel recanalization and inflammation along with lymphocyte infiltration around the vessels was observed. These results revealed that long-term IVM administration has a gradual adulticidal effect on heartworms in canines and embolism. From recovery findings showed pulmonary embolism in the CT image and histopathologic examination, long-term IVM administration can potentially be used for adulticidal treatment in clinical cases where it is difficult to perform surgical extirpation and administer arsenic therapy.

Virtopsy in a Red Kangaroo with Oral Osteomyelitis

Abstract This report describes the use of computed tomography (CT) in a nondomestic species. Postmortem CT was performed on a red kangaroo (Macropus rufus) and a diagnosis of oral osteomyelitis was made. CT examination revealed bony remodeling of the right mandible, an intraosseous lesion of the right temporal bone, muscle necrosis around the right mandible, and the absence of the right, first, upper molar tooth. Cardiac and intrahepatic gas and a distended intestine due to postmortem gas accumulation were also seen. All the lesions identified with CT were also identified by conventional necropsy, except the cardiac and intrahepatic gases. Virtopsy may be a useful procedure for the noninvasive identification of cause of death and as a guide for necropsy in animals.

Measurement of canine pancreatic perfusion using dynamic computed tomography: influence of input-output vessels on deconvolution and maximum slope methods.

OBJECTIVE We investigated whether the prerequisite of the maximum slope and deconvolution methods are satisfied in pancreatic perfusion CT and whether the measured parameters between these algorithms are correlated. METHODS We examined nine beagles injected with iohexol (200 mgI kg(-1)) at 5.0 ml s(-1). The abdominal aorta and splenic and celiac arteries were selected as the input arteries and the splenic vein, the output veins. For the maximum slope method, we determined the arterial contrast volume of each artery by measuring the area under the curve (AUC) and compared the peak enhancement time in the pancreas with the contrast appearance time in the splenic vein. For the deconvolution method, the artery-to-vein collection rate of contrast medium was calculated. We calculated the pancreatic tissue blood flow (TBF), tissue blood volume (TBV), and mean transit time (MTT) using both algorithms and investigated their correlation based on vessel selection. RESULTS The artery AUC significantly decreased as it neared the pancreas (P<0.01). In all cases, the peak time of the pancreas (11.5±1.6) was shorter than the appearance time (14.1±1.6) in the splenic vein. The splenic artery-vein combination exhibited the highest collection rate (91.1%) and was the only combination that was significantly correlated between TBF, TBV, and MTT in both algorithms. CONCLUSION Selection of a vessel nearest to the pancreas is considered as a more appropriate prerequisite. Therefore, vessel selection is important in comparison of the semi-quantitative parameters obtained by different algorithms.

Computed tomography of the prostate gland in apparently healthy entire dogs

OBJECTIVES To describe the computed tomography (CT) features of the prostate gland and determine prostate size using CT in entire male dogs. METHODS The prostate gland was evaluated in 35 dogs. Morphological features including homogeneity, delineation, shape and intraprostatic differentiation were assessed. Height, length, width, area, volume and attenuation values of the prostate gland were measured. Ratios of prostatic height (rH), length and width to the sixth lumbar vertebral body length were calculated. Relationships of prostatic dimensions with body weight and age were evaluated. RESULTS The prostate gland was homogeneous in 29 dogs on non-contrast images and 18 of 24 dogs on postcontrast images. Transverse images revealed a semi-oval prostate gland in 29 dogs and irregularly shaped prostate gland in 6 dogs. A prominent median septum was observed in postcontrast images. Significant positive correlations were found between body weight and age and all prostatic dimensions except between age and rH. The mean ± sd values for attenuation were 59·3 ± 9·1 and 121·3 ± 22·7 HU in non-contrast and postcontrast image, respectively. CLINICAL SIGNIFICANCE CT can be useful for evaluating morphological features of the prostate gland. Prostatic length or width is a better measure than height for computed tomographic estimation of prostate size.

Influence of osmolarity of contrast medium and saline flush on computed tomography angiography: Comparison of monomeric and dimeric iodinated contrast media with different iodine concentrations at an identical iodine delivery rate

PURPOSE To evaluate the influence of osmolarity of iodinated contrast media and saline flush on the contrast effect in thoracic computed tomography angiography (CTA) at an identical iodine delivery rate (IDR). MATERIALS AND METHODS Seven beagles were used in a cross-over experiment. The contrast media used were iohexol 350 mgI/ml (IOH350; osmolarity 844 mmol/kg) and iodixanol 320 mgI/ml (IDX320; osmolarity 290 mmol/kg). Each contrast medium was administered to groups with and without saline flush at 40.0 mgI/kg/s for all experiments. Dynamic CT scanning was performed at the ninth thoracic vertebra level. The peak value, area under the curve (AUC), and time to peak (TTP) were calculated from the time attenuation curves of the pulmonary artery and aorta. RESULTS There was no significant difference between IOH350 and IDX320 with or without saline flush in the peak values for the pulmonary artery and aorta. AUC was significantly higher in groups with saline flush for both contrast media and arteries (p<0.05) with no significant difference between contrast media. TTP was significantly longer in groups with saline flush than without saline flush for both contrast media and arteries (p<0.05), with no significant difference between contrast media. CONCLUSIONS There were no significant differences in the contrast effects of monomeric IOH350 and dimeric IDX320 in thoracic CTA when used at an identical IDR. Moreover, saline flush prolonged the peak duration at 600 mgI/kg.

Effect of a saline chaser for contrast enhancement of computed tomographic angiography in cattle.

Computed tomographic angiography was performed on nine normal Holstein calves in a crossover method to investigate the effect of a saline chaser for enhancement of the maxillary arteries and dorsal sagittal sinus. One group was administered a contrast injection (600 mg iodine/kg at 4 ml/s) followed by 50 ml of a saline chaser at the same rate as the contrast material. The second group was administered a contrast injection without a saline chaser. Addition of the saline chaser to the contrast material resulted in a higher peak attenuation in the maxillary artery (244.45 ± 36.19 v 202.20 ± 27.07, P<0.05) and dorsal sagittal sinus (241.2 ± 31.51 v 198.88 ± 21.09, P<0.05). These results indicate that a contrast injection followed by saline chaser increased uptake in contrast-enhanced CT.

The relationship between the size of caudolateral curvilinear osteophyte of the canine femoral neck and the radiographic view.

Caudolateral curvilinear osteophyte (CCO), an osteophyte at the site of joint capsule attachment on the caudal aspect of the femoral neck, has been advocated as a radiographic criterion for coxofemoral subluxation. The correlation between the presence of CCO on radiographs (radiographic-CCO), the size of the CCO (CCO index) on three-dimensional computed tomographic (CT) images, and hip evaluation using transverse CT images was assessed in 22 Border Collies. CCOs were detected on the radiographs and CT images of 32% and 100% femurs, respectively. The CCO index correlated significantly with radiographic-CCO, but a large CCO index did not necessarily imply that the CCO was visible on radiographs. Hence, radiographic-CCO findings should be used cautiously in hip evaluation of Border Collies.

Anatomical variation of arterial supply to the rabbit spleen

The rabbit, which is widely used as an experimental animal and is also popular as a companion animal, has a flat and elongated spleen with the longitudinal hilus running along its visceral surface. The spleen receives via the hilus an arterial supply that is essential for splenic nutrition and normal functioning. However, the distribution and variation of the arteries to the spleen have not been studied in detail. This study investigated anatomical variations of splenic arterial supply in 33 New Zealand White rabbits with a colored latex injection into arteries. We also examined whether the length of the spleen correlated with the number of the splenic branches of the splenic artery. The splenic artery always arose as the first independent branch of the celiac artery and ran along the splenic hilus to usually provide 6 (range, 3 to 10) splenic branches to the spleen. There was a moderate correlation (R=0.6) between the number of splenic branches and the longitudinal length of the spleen. The splenic branches often arose as a trunk or trunks in common with short gastric arteries. The number of common trunk(s) was usually 1 (range, 0 to 4). The data showed that the pattern and number of arterial branches to the spleen varied according to the individual animal, suggesting that such variations should be considered when performing experimental and veterinary surgical treatments in rabbits.